Thermochemical combustible gas detector

Abstract

A thermochemical combustible gas detector having a resistor bridge including a thermistor which is sensitive to combustible gases and a thermistor which compensates the effects of unmeasured parameters and components upon the former thermistor. The supply diagonal of the bridge is connected to a power source via a compensating voltage stabilizer having an adjusting link and two amplifier-comparator links one of which is auxiliary. The detector further includes two conventional auxiliary resistors which are interconnected in series and form an additional resistor bridge with the thermistors of the main bridge. The input of the first amplifier-comparator link is connected to the measuring diagonal of the main bridge. The input of the auxiliary amplifier-comparator link is connected either to the measuring diagonal of the additional resistor bridge, or to one of the auxiliary resistors.

What is claimed is: 
     
       1. A thermochemical combustible gas detector comprising: a resistor bridge having a first arm including a thermistor sensitive to combustible gases,   a second arm adjacent to said first arm, said second arm including a thermistor for compensating the effect of unmeasured parameters and components of the atmosphere upon said sensitive resistor,   a third arm and a fourth arm, each including a conventional resistor;   an additional resistor bridge having one arm including a conventional auxiliary resistor,   a second arm including another conventional auxiliary resistor,   the third and fourth arms of said additional bridge forming said sensitive and compensating thermistors of said first resistor bridge;   a compensating voltage stabilizer comprising:   an amplifier-comparator link with input connected to the measuring diagonal of said resistor bridge,   an auxiliary amplifier-comparator link with input connected to the measuring diagonal of said additional resistor bridge,   an adjusting link with input connected in parallel to each output of the amplifier-comparator links, an output of said adjusting link being connected to the supply diagonal of both of said bridges;   a signal indicator of impermissible concentrations of combustible gases in the atmosphere and having an input connected to the output of any of said amplifier-comparator links of said stabilizer;   a power source connected to said stabilizer and signal indicator.   
     
     
       2. A thermochemical combustible gas detector comprising: a resistor bridge having   a first arm including a thermistor sensitive to combustible gases,   an adjacent arm including a thermistor for compensating the effects of other unmeasured parameters and components of the atmosphere upon said sensitive thermistor,   each of two remaining arms of said bridge including a conventional resistor;   two conventional auxiliary resistors connected in series to the supply diagonal of said resistor bridge;   a compensating voltage stabilizer comprising:   an amplifier-comparator link with input connected to the measuring diagonal of said resistor bridge,   an auxiliary amplifier-comparator link with input connected to any of said auxiliary resistors,   an adjusting link with input in parallel with the outputs of said amplifier-comparator links, an output of said adjusting link being connected to the supply diagonal of said resistor bridge;   a signal indicator of impermissible concentrations of combustible gases in the atmosphere and having an input connected to the output of any of said amplifier-comparator links of said stabilizer;   a power source connected to said stabilizer and said signal indicator.   
     
     
       3. A thermochemical combustible gas detector comprising: a power source;   a resistor bridge having:   an arm including a thermistor sensitive to combustible gases,   an adjacent arm including a thermistor for compensating the effects of other unmeasured parameters and components of the atmosphere upon said sensitive thermistor,   each of two remaining arms of said resistor bridge including a conventional resistor;   an additional resistor bridge comprising:   an arm including a conventional auxiliary resistor;   a second arm including another conventional auxiliary resistor,   two remaining arms of said additional bridge forming said sensitive and compensating thermistors of said first resistor bridge;   a compensating voltage stabilizer comprising:   an amplifier-comprator link including:   a tunnel diode,   a voltage transformer with primary winding in series with said tunnel diode,   said tunnel diode and primary winding of the transformer being connected to the measuring diagonal of said first resistor bridge,   a transistor with input connected to the secondary winding of said transformer,   a diode with cathode connected to the emitter of said transistor and to the latter's output circuit;   an additional amplifier-comparator link including:   a tunnel diode,   a voltage transformer with primary winding connected in series with said tunnel diode, said tunnel diode and primary winding of the transformer being connected to the measuring diagonal of said additional resistor bridge,   a transistor with input connected to the secondary winding of said transformer,   an adjusting link including:   an RC circuit comprising a resistor and a capacitor connected in series and connected to said power source, the capacitor of said RC circuit being connected in parallel via said diode of the first amplifier-comparator link and with the emitter-collector circuit of said transistor of the same link, said capacitor also being directly connected to the emitter-collector circuit of said transistor of the auxiliary amplifier-comparator link,   a voltage divider having two resistors connected in series,   an output transistor through whose collector circuit said voltage divider and the supply diagonal, which is common for both of said bridges, are connected to said power source,   an input transistor with base connected to the capacitor of said RC circuit, the emitter of said transistor being connected to said voltage divider and the collector of said input transistor being connected to the base of said output transistor;   a signal indicator of impermissible concentrations of combustible gases in the atmosphere connected to said power source and comprising:   a transistorized multivibrator with input connected to the emitter of the transistor of said first amplifier-comparator link,   an electromagnetic relay connected to the output of said multivibrator,   a signal lamp connected to said power source via contacts of said relay.